Exhaust-pressure-control valve



Feb. 25, 1930.

H. RCIJWNTREE 1,748,496

EXHAUST PRESSURE CONTROL VALVE 7 Filed 001;. 24, 1927 2 Sheets-Sheet l.272 WWZZZ mm?) .03am

351 attozmeqgmmw Feb. 25, 1930. H. ROWNTREE EXHAUST PRESSURE CONTROLVALVE Filed Oct. 24, 1927 2 Sheets-Sheet 2 Patented Feb. 25, 1930 UNITEDSTATES PATENT OFFICE HAROLD ROWNTREE, OF SGAR SDALE, NEW YORK, ASSIGNORTO NATIONAL PNEU- MATIG COMPANY, OF NEW YORK, N. Y., A CORPORATION OFWEST VIRGINIA ExHAUST-PRESSURE-CONTROL VALVE Application -filed October24, 1927. Serial No. 228,135.

again move after havingbeen stopped by an obstruction.

A further object of this invention is the provision of a device of thistype which is adapted to control the speed of the engine to prevent theslamming of doors operated thereby.

A further object of this invention is the provision of an exhaust valvefor fluid engine which is controlled by differential pistons under thecontrol of the fluid from the fluid source and the fluid from theexhaust end of the engine.

This and many other objects are secured by means of the constructiondisclosed hereinafter. This invention resides substantially in thecombination, construction, arrangement and relative location of parts aswill be more clearly brought out in the following disclosure.

Referring to the drawings- Figure 1 is a longitudinal cross sectionalview through the engine of the exhaust controlling device, and

Figure 2 is an enlarged cross sectional view 4 through the valve whichcontrols the exhaust and provides a nonslamming effect for the engine.

It is usual in the commercial employment of fluid operated engines foroperating doors and the like to provide means for preventing theslamming of the doors when movement is interrupted during the closingmovement thereof. It is also usual to provide some means for preventingthe slamming of the doors near the end of their closingmove ment. Bymeans of the device of this invention both these functions are securedby means of a relatively simple control valve which may mostconveniently be mounted directly on the fluid operated engine. By

- means of the construction devised by me it is possibleto secure theadvantage of no leakage of fluid pressure through the exhaustingcylinder when the door is held up by an obstruction during its closingmovement. There is also no possibility of the door creepmg open or,.when forced partially open, to admit pressure to cause the openingmovement to continue.

The arrangement of this invention also eliminates the necessity of afree exhaust port as it is now used in the cylinder of the presenttype-engines and as a result the piston cups will wear longer. Doorengines provided with the device of this invention cause the doors tostart promptly upon energization of the same, to continue with a steadymovement, and prevent jamming and slamming of the doors when they arereleased after being held up by an obstruction.

7 Referring to the drawings, the engine is shown as comprisin a cylinder1 having two end caps 2 and 3. glidably mounted within the cylinder arethe two pistons 4 and 5 which are rigidly joined together by means of apiston rod 6. The piston rod has the toothed rack 6' thereon whichmeshes with a pinion .and shaft (not shown) for connection to the deviceto be operated. The leather piston cup 7 is secured to the-piston 4 bymeans of the collar 9 and nut 9'. The leather piston cup 8 is likewisesecured to the piston 5 by means of the collar 10 and nut 10. Each endof the cylinder is connected through the passages 11 and 12 with thevalve casmg 14 through the passages 33 and 34 which are formed in thesupport 13 with the valve cas-.

ing.

casing 14 for rotation on the valve stem 20. The valve 15 is providedwith two ports 16 and 17 which extend only partially there the threadedopening 24. The ,chamber 22 forms a small cylinder within which a smallpiston 27 operates. A larger cylinder 23 is provided in alignment withthe chamber 22 A. rotary valve 15 is mounted within thewithin which thelarger piston 28 moves. The pistons 27 and 28 are both mounted on thesame connecting rod 29 upon the end of which is provided a valve 30. Thepiston 28 is larger than the piston 27 and this arrangement provideswhat is known as a differential device.

The chamber 23 is connected by means of the pipe 25 with a passage whichopens directly in the path of the ports 16 and 17. The space between thetwo pistons is vented to the atmosphere through the passage 26 in thecylinder wall. The movement of the valve 30 to the left is resisted bymeans of the spring 31. Twp exhaust ports 32 are provided in the valveand piston casing and are arranged to be disconnected with the interiorof this casing when the valve 30 is seated; The lever 35 is mounted onthe valve stem 20 when operating the valve.

In this disclosure the mechanism which connects the pistons and thelarge cylinder 1 with the device to be operated by the engine, such asdoors, is notshown for sake of simplicity since it forms no part of thisinvention.

With the valve in the position shown in Figure 1 fluid pressure from thesource is admitted through the opening 24 into chamber 22 of the valvecasing 14. Since the hole 19 extends all the way through the valve 15 afluid pressure will, therefore, pass through passages 33 and 11 to theright hand end of builds up sufficiently to move the pistons 27 and 28to the right valve 30 will be unseated and the fluid in chamber 23 willbe exhausted through the ports 32. This occurs notwithstanding the factthat the fluid pressure from the source exists in chamber 22 since thearea of piston 28 is greater than that of piston 27. Should the doormeet with an obstruction so as to stopthe movement of pistons 4 .and 5the fluid will exhaust from chamber 23 until the pressure on piston 27is greater than that on piston 28 when the valve 30 will be moved to theleft..and will shut off any further exhaust of the fluid from the lefthand end of cylinder'l. When the obstruction is removed from the doorthe pistons 4 and 5 will again begin to move to the left and whenpressure in chamber 23 has been built up sufiicientlv to force pistons28 and 27 to the right the fluid can then exhaust through the ports 32.

The relative areas of pistons 27 and 28 determine the relation betweenthe exhaust pressure that exists in the exhausting end of the cylinderand the operating pressure. and, therefore, a constant speed operationis achieved that is not disturbed by the door being held up during theclosing movement lating the speed of its operating stroke.

I am well aware that many changes in the details of construction andrelative association of parts will readily occur to those skilled in theart and I do not, therefore, desire to be limited to the constructionshown for purposes of illustration but rather to the scope of theinvention defined in the appended claims.

What I seek to secure by United States Letters Patent is:

' 1. The combination with a fluid pressure engine for operating doorsand the like having a cylinder, double acting pistons therein and apassage leading to each end of the cylinder of means communicating withsaid passages for controlling the admission and exhaust of fluid to saidcylinder, said means comprising a valve chamber, a valve therein, acasing having connected differential pistons therein, the portion of thecasing in which the smaller piston moves being in di rect connectionwith said valve chamber, a. connection from the valve casing to the por.tion of the casing in which the larger piston moves and a valvecontrolled by the larger piston for controlling an exhaust port, thevalve in said valve casing controlling the flow f fluid from theexhausting end of the engine cylinder. the differential pistons and thevalve controlled by; the larger piston acting to cut off the exhaust offluidfrom the engine cylinder when the door meets an obstruction. 2. Thecombination with a fluid pressure engine for. operating doors and thelike hav-.

ing a cylinder, double acting pistons therein and a passage leadingtoeach end of the cylinder of means communicating with said passages forcontrolling the admission and exhaust of fluid to said cylinder, saidmeans comprising a valve chamber, a valve therein, and a'casing havingconnected differential pistons therein. the portion of the casing inwhich the smaller piston moves being in direct connection with saidvalve chamber, a connection from the valve casing to the portion of thecasing in which the larger piston moves and a valve controlled by thelarger piston for controlling an exhaust port, the valve in said valvecasing controlling the flow of fluid from the exhausting end of theengine cylinder, the differential pistons and the valve controlled bythe larger piston acting to cut off the exhaust of fluid from the enginecylinder when the door meets an obstruction, said valve in said casingacting in conjunction with said passages to open either end of theengine cylinder to admission or exhaust of fluid.

3. The combination with a fluid pressure engine for operating doors andthe like having a cylinder, a double acting piston therein and a passageleading to each end of the cylinder of a valve casing, a valve in saidcasing for controlling said passages, a fluid pressure 1 connection tosaid casing, a differential piston structure including a casing; anexhaust valve controlled by said differential piston structure, meansfor applying fluid pressure to the smaller area of said diflerentialpiston structure and a connection between said first mentioned valve andthe end of the casing in which the larger area of saiddifi'erentialpiston structure operates, said exhaust valve acting toopen the differential piston casing to the atmosphere when the forceproduced by the pressure therein acting on the larger area of thedifl'erential piston structure is greater than the force produced by thepres- 2:5 sure acting on the smaller area of the differential pistonstructure.

In testimony whereof I have hereunto set my7hand on this 22nd day ofOctober A. D. 192

HAROLD ROWNTREE.

